Troubleshooting KEPServer and PV+ (Modbus)

lolproe

Member
Join Date
May 2013
Location
Canada
Posts
11
Hey guys,

I posted a question a few days ago about using a PanelView Plus with an AB Micro850 PLC. The response I got suggested that I use KEPServer on the PV+ to communicate with the PLC. Right now I have the Micro850 connected to the PV+ with a 1761-CBL-PM02 and a null modem adapter.

I've tried configuring a project following the "Modbus Applications" document by Rockwell, but the runtime on the PV+ doesn't work. Whenever I try to write to a tag, it gives me an error saying "Unable to write value 'X' to item 'ModbusRTU.PLC.Y", where X and Y are the values being written and the tags. I'm fairly confident that the OPC server itself is configured properly, because the tags I made in KEPServer all showed up in the tag browser in FTView Studio, and when I initially run my application on the PV+ I get an information banner saying "Starting Modbus RTU Serial device driver" "Modbus RTU Serial Device Drive V5.7.336.0".

Since the PV+ is telling me that it's loading the Modbus RTU Serial device driver, my assumption is that it's correctly linked to the KEPServer project which is telling it to use that driver for communications. I'm also confident that the Micro850 is accessible. I had an RS-485 to USB adapter lying around, so I changed the Micro850 from RS-232 to RS-485, connected it through the adapter to my computer, and used Simply Modbus to send it packets. These packets were read correctly, so the Micro850 isn't having problems with Modbus. All the basic settings in Simply Modbus (address, baudrate, parity, address, data bits, stop bits) match the KEPServer ones, with the only difference being that I switched the Micro850 to RS-485 mode so it would work with the adapter.

Based on all this, I'm guessing I have a driver problem. It seems like KEPServer is properly loaded on the PV+ and it has roughly the right settings, but some setting I don't understand is causing the communications to fail. The ID I'm using in KEPServer is SERIAL 1 and that's mapped to COM1 on the PV+, and that's about the only possible problem I can think of.

I'm pretty stumped at this point. If anyone has experience with this and has an idea of what might be wrong, I'd appreciate it a ton. I'm also wondering if there's any decent way to troubleshoot this problem in-depth. The "Modbus Applications" document suggests that you can test the connection using the OPC Quick Client from within KEPServer, but this doesn't make a lot of sense to me. The PV+ and PLC are connected using RS-232, so I don't really understand how running this client on my computer would do anything. Is there a way to set up KEPServer so that the OPC Quick Client is connected (over Ethernet?) to the running application?
 
My first thought was that you had left the Micro 850 set for RS-485 and then connected the PanelView over RS-232, but it sounds like you've got that covered.

The Serial1 -> COM1 issue is a common mistake, too: your USB/RS485 converter was almost certainly not COM1, right ? But it sounds like you do correctly have SERIAL1 associated with your KepServer project onboard the terminal.

Make sure that you don't have an RSLinx Enterprise DF1 driver configured that will also attempt to use COM1 onboard the PanelView Plus terminal. There's nothing automatic to keep RSLinx Enterprise and KepServer Enterprise from fighting over the same hardware.

To test the KepServer project, I would point it toward the COM port used by your USB/RS485 converter and use the OPC Quick Client on your development PC.

If you can get an ordinary serial port or a USB/RS232 converter, you could also test by connecting the PV+ to your computer and running a Modbus RTU Slave emulator (or just a terminal program to look at the raw bytes).
 
Make sure that you don't have an RSLinx Enterprise DF1 driver configured that will also attempt to use COM1 onboard the PanelView Plus terminal. There's nothing automatic to keep RSLinx Enterprise and KepServer Enterprise from fighting over the same hardware.

This sounds reasonable, but I'm not entirely sure how to determine if this is the case since I'm not very familiar with RSLinx. In my application that I copied over, the only things in the Runtime tab are Backplane and Ethernet connections. When I go to my terminal settings and look at RSLinx Enterprise Configuration, Virtual Backplane and Ethernet are the only drivers listed, so is that confirmation of this?

To test the KepServer project, I would point it toward the COM port used by your USB/RS485 converter and use the OPC Quick Client on your development PC.

If you can get an ordinary serial port or a USB/RS232 converter, you could also test by connecting the PV+ to your computer and running a Modbus RTU Slave emulator (or just a terminal program to look at the raw bytes).

Within KEPServer Enterprise, I only have the options of pointing to ID's SERIAL 1 - SERIAL 16. There are no options to point to COM ports directly, so I'm not sure how I could get it working on my PC.

I realized I had a copy of the KEPServerEX trial lying around, so I've been playing around with that since it does allow me to select COM ports. When using the RS-485/USB converter, the communications work. The communications seem really inconsistent (every third or fourth read fails) but at least the tags are updating.

I think I might have found the problem though. Right now, I'm using a 30 day trial of FTView Studio. I was disappointed when I found out that KEPServer Enterprise had a 2 hour demo (not very useful when your entire application depends on it) and called up my AB distributor, and they sent me an activation for a longer demo. What I didn't realize is that the demo activated KEPServer Enterprise v4.5 instead of v5.7. When I made my project, I did set the OPC server to use KEPServer Enterprise v4, but my PV+ says it has KEPWare v5.7 installed on it. So I bundled a KEPServer Enterprise v4 project with my executable even though my PV+ has KEPServer Enterprise v5.

I'm not positive that this is a problem, but it's looking like a good culprit to me. I'll call them back and see if I can get another activation for the newer version of KEPServer.
 
The fact that you don't have an RS-232 driver listed either in RSLinx Enteprise on your development PC or on the PV+ terminal is good; that proves that there is no serial port resource conflict.

In general SERIAL 1= COM1.

I'm not qualified to troubleshoot or explain mixed versions and activations of KepServer Enterprise and EX and FactoryTalk View Studio.
 

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